Article decelerator for air conveyor

ABSTRACT

A momentum decelerator for air conveyors having the preferred form of a rotatable turnstile positioned above the conveyor with a downwardly directed arm in the path of oncoming articles. The turnstile is rotated upon impact of the downward arm with the moving article to be slowed down and this rotation results in a second arm applying a decelerating force to the article in proportion to the momentum of impact. The decelerator distinguishes between a single article traveling along the conveyor and an accumulated group of articles, and operates only on the first member of a group, allowing the others of the group to pass without further restraint so as to prevent stopping of grouped articles on the conveyor.

[451 Sept. 25, 1973 ARTICLE DECELERATOR FOR AIR CONVEYOR [75] Inventor:Stanley E. Hurd, Sunnyvale, Calif.

[73] Assignee: The Motch & Merryweather Machinery Company, Euclid, Ohio[22] Filed: Jan. 6, 1972 [21] App1.No.: 215,882

Related U.S.' Application Data [63] Continuation-in-part of Ser. No.7,090, Jan. 30, 1970,

8/1960 Place 193/32 X 12/1902 Dedrick 193/32 X Primary Examiner-Even C.Blunk Assistant Examiner-W. Scott Carson Attorney-Patrick J. Walsh [57]ABSTRACT A momentum decelerator for air conveyors having the preferredform of a rotatable turnstile positioned above the conveyor with adownwardly directed arm in the path of oncoming articles. The turnstileis rotated upon impact of the downward arm with the moving article to beslowed down and this rotation results in a second arm applying adecelerating force to the article in proportion to the momentum ofimpact. The'decelerator distinguishes between a single article travelingalong the conveyor and an accumulated group of articles, and operatesonly on the first member of a group, allowing the others of the group topass without further restraint so as to prevent stopping of groupedarticles on the conveyor.

2 Claims, 4 Drawing Figures ARTICLE DECELERATOR FOR AIR CONVEYOR This isa Copntinuation in Part of Ser. No. 7,090 filed Jan. 30, 1970 nowabandoned.

BACKGROUND OF THE INVENTION AND PRIOR ART One of the difficultiesassociated with the transporting of breakable articles by air conveyorsis maintaining and controlling their speed. If the air pressure producedis too low, an insufficient force will not propel an accumulated groupof articles, nor will it restart the movement of such articles shouldthey become stopped at some point along the conveyor. On the other hand,if the air pressure is increased sufficiently to propel an accumulatedgroup of articles or to restart stopped articles, the continuingapplication of such force to a single article will eventually acceleratethe article, if the conveyor is long, to progressively increasing itsspeed to the point of where impact of such article with another articleor other obstacle will result in forces that may be sufficient to break,rupture, or otherwise damage the article.

Various efforts have been made have been made to regulate and controlthe speed of such conveyed articles. One attempted solution is toadjustably regulate the pressure in the air plenum at differentdownstream sections by using regulating valves, changing the number orarrangement of the slots, or by other techniques to regulate the airforces. However, it is quite difficult to so adjust the air pressure andflow at different sections of the conveyor so as to always providesufficient pressure for starting and conveying accumulated loads and yetnot producing such excessive pressure as to unduly accelerate individualarticles. Additionally, such air regulation systems have been found toincrease the complexity and cost of the conveyor system beyond thatwhich is considered desirable.

An alternative proposed solution is to provide a constant drag orconstantly acting retarding force on the air conveyed articles. However,such constant drag force does not distinguish between articles travelingalone and those moving in an accumulated group. Therefore, if theconstant drag is sufficient to properly slow down an article travelingalone, it will entirely stop an accumulated group of articles andprevent proper feeding of such articles by the conveyor.

STATEMENT OF THE INVENTION The present invention provides acomparatively inexpensive solution to the problem of preventing articlesfrom being conveyed at excessive speeds yet providing sufficient airforces to restart stopped articles and to propel acumulated groups ofarticles. This is performed by spacing a series of article deceleratorsat downstream distances along the length of the conveyor, each of whichintermittantly engages the moving articles as they pass by and providesa sufficient decelerating force to the engaged article to regulate andmaintain a proper speed.

Each such decelerator is essentially a passive force redirectingmechanism that is struck or impacted by the moving article as it passesby and functions to apply a variable force against the articlessufficient to decelerate the article. The force applied to the articleis in proportion to its momentum of impact with the decelerator andtherefore the article is slowed down only in proportion to its speedwhen stiking the decelerator.

The decelerator also uniquely functions to apply the force to only thefirst one of an accumulated group of articles and permits the remainingarticles in the group to pass by without further interference. Thisinsures that an accumulated group of end-to-end articles will not bestalled to an extent that is beyond the ability of the conveyor torestart.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view schematicallyillustrating an air conveyor and one preferred turnstile typedecelerator according to the invention,

FIG. la and lb are side views schematically illustrating the forceredirecting mode-of-operation of the decelerator of FIG. 1, and

FIG. 2 is a side view schematically illustrating the passage of anaccumulated group of articles without further interference by thedecelerator.

Referring to FIG. 1, the air conveyor 10 is of the general constructionsuch as shown in earlier US. Pat. No. 3,131,974 including a suitablesheet metal conduit 10 having a flat upper surface or bed with one ormore rows of inclined openings 11 spaced apart lengthwise or downstreamalong the conveyor. As best shown in FIGS. la and 1b, the air jets l2emerging from the inclined openings 11 have a component directedupwardly to suspend or lift the articles 13 to be conveyed and a secondcomponent directed parallel to the surface of the bed to propel thesuspended articles.

It will be appreciated that even a constant compo- 1 nent of propellingair force acting on the articles 13 will accelerate the articles, and ifthe conveyor is sufficiently long this force will soon increase theirspeed beyond that desired. For periodically decelerating the articles, aplurality of turnstile type decelerators are i spaced apart at suitableintervals downstream above the conveyor bed. Each decelerator isprovided with at least two angularly displaced and interconnected armssuch as 23 and 25 that are together pivotable about an axis along shaft22, arranged transversely to the direction of the air flow from theconveyor.

In the preferred construction shown in the drawings, each decelerator isprovided withthree angularly displaced U-shaped arms 22,24, 25 in aturnstile or star shaped configuration attached to the central shaft 22.The shaft 22 is suitably supported to pivot or rotate in bearingsupports 20 and 22, permitting the arms to pivot about the axis of theshaft 22.. A toothed wheel or ratchet 17 is provided on the shaft 22 andits teeth are engaged by a flexible spring blade 18, the engagement ofblade 18 with the ratchet forming a resilient stop to prevent theturnstile from freely rotating about the axis of shaft 22. v

In the absence of this temporary stop, the horizontal component of airflow from the conveyor, acting upon the legs of the turnstile; wouldspin the turnstile about the axis of shaft 22. However, the spring blade18 and toothed wheel 17 provide a sufficient restraining force tonormally maintain the turnstile in the stationary position of figures land la. The teeth 170, b, c on the ratchet wheel 17 are so arranged inphase relationship to the angular location of the legs that theturnstile is normally pivoted by the air flow until one of the legs 23,24 or 25 is positioned downwardly, as shown in FIG. 1 and FIG. la,disposed in the path to intercept oncoming articles 13 traveling alongthe conveyor. As shown in FIG. 1 the preferred arrangement of teeth of17a.b. and c on the ratchet wheel is to locate teeth l7a,b. and c suchthat spring blade 18 will engage tooth 17a to stop the turnstile withcushioned roller positioned in the path to intercept oncoming articles.Similarly, teeth 17b and 170 are effective to position cushioned rollers14 and 16 respectively in the path of oncoming articles when springblade 18 engages such ratchet teeth 17b and 17c. By this arrangement theturnstile has a tendency to rotate under the influence of the air flowalong the conveyor surface until one of the legs is positioned tointercept oncoming articles. At the base of each of the U-shaped legs isprovided a cushioned roller, 14, 15 and 16 that may be of foam rubber orthe like whose purpose is to cushion the impact between the articles 13being conveyed and the decelerator.

In operation, as generally illustrated in FIGS. la and 1b, the forwardor leading side of articles 13 traveling the conveyor collide with thedownwardly directed leg of the decelerator, striking the cushionedroller 15 provided about this leg 25. The momentum of impact involved isproportional to the weight and to the speed of travel of articles 13,and this impact rapidly pivots the turnstile in a counterclockwisedirection, as shown by the arrowed line. Rotation of the turnstile,brings the next arm 23 of the turnstile downwardly, and the cushionedroller 14 about this arm strikes the top surface of the article 13 withsubstntially the same momentum as provided by the initial collision, allas illustrated in FIG. 1a. This impact momentarily pushes the articlesdownwardly against the conveyor bed, slowing its speed as desired.

It will be noted that the decelerating force or momentum is inproportion to the speed of the article 13, since the turnstile merelyoperates to redirect this force backwardly onto the article 13.Consequently, the faster the article 13 is traveling, the greater willbe the decelerating force to slow down the article.

After the second arm 23 of the turnstile strikes the top surface of thearticle 13, its energy is substantially dissipated and the two legs 23and 25 remain in the dis placed angular position shown in FIG. lb untilthe article 13 has been restarted by the air jets and propelledunderneath both of the arms 23 and 25 in its continuing travel down theconveyor. When. the article has completely past by the decelerator legs,the upwardly inclined jets of air acting on the turnstile legs againrotate the turnstile to its normal position of FIG. 1 or FIG. la, withone leg being disposed vertically facing downward in an interceptposition with any further articles traveling the conveyor" and with theother two legs positioned upwardly as shown. When the turnstile is againso positioned, the spring arm 18 engages the next tooth of the ratchetwheel 17 to stabilize or maintain the turnstile in this normal angularposition.

It will be observed that each article traveling alone down the conveyorwill be momentarily decelerated as described above by each of theplurality of spaced decelerators, which are spaced apart at distancescorresponding to the maximum speed that is desired that the articlereach in its travel. However, in the event that an accumulated group ofsuch articles 13 are traveling in back-to-back engagement along theconveyor, or are traveling closely spaced apart from one another asshown by units 130, 13 b, and 13a in FIG. 2, each of the deceleratorsoperates only upon the first one of the accumulated group of articles,momentarily slowing the entire group that are in contact, and thenallowing the entire group to pass by without further interference. Thisresults from the fact that after completing the impact with the firstarticle 13 of the group, the legs, 23 and 25 (in FIG. lb) of theturnstile are in the displaced position shown above the article and outof contact with the article 13. The air jets emanating from the conveyor12 are substantially blocked by the remaining accumulation of articles13 from reaching the turnstile, and therefore cannot re-center theturnstile to its normal intercept position of FIG. 1 or FIG. 10 untilall of the articles of the accumulated group have past by.

This is, of course, the desired functional mode-ofoperation of thedecelerator since otherwise if a decelerating force was applied to eacharticle of an accumulated group it could create a complete stoppage ofthe flow of the articles along the conveyor. Thus, the preferreddecelerator provides a discriminating mode-ofoperation that serves toregulate the speed of articles traveling alone down the conveyor whileat the same time does not overregulate and completly stop and clog up anaccumulation of articles being conveyed.

As will be appreciated by those skilled in the art the construction ofthe decelerator mechanism may be varied while performing the samefunction. For example, it is not required that three legs be providedsince for any single decelerating action, only two legs are needed 1 forimpact with the front side and top of the article. Additionally, otherforms of temporary stops or restraining devices may be employed forinsuring that a downwardly facing decelerator leg is repositioned aftereach cycle of operation in readiness to impact with the next oncomingarticle along the conveyor. Since these and 1 many other changes may bemade by those skilled in the art without departing from the spirit andscope of this invention, this invention is to be considered as beinglimited only by the followning claims.

What is claimed is:

1. An air conveyor comprising the combination of a conveyor surfacehaving perforations therein, means for supplying a flow of air throughsaid perforations to lift and move articles along said conveyor; and amomentum decelerator comprising a turnstile member having a plurality oflegs extending therefrom, said turnstile member being mounted forrotational movement above the conveyor surface so that the dependinglegs may contact and decelerate articles moving along the conveyor, saidturnstile member being rotated by air flowing through said perforations,and means for stopping the turnstile member from further rotation underthe influence of said flowing air when a depending leg is rotated to aposition in the path of articles moving along the conveyor.

2. An air conveyor comprising the combination of a conveyor surfacehaving perforations therein, means for supplying a flow of air throughsaid perforations to lift and move articles along said conveyor; and amomentum decelerator comprising a turnstile member having a plurality oflegs extending therefrom, said turnstile member being mounted forrotational movement above the conveyor surface so that the dependinglegs may contact and decelerate articles moving along the conveyor, saiddepending legs being spaced from each other so that when a movingarticle on the conveyor contacts and rotates the turnstile member, afollowing leg on the rotating turnstile member contacts said movingarticle causing further deceleration of the article on the conveyor,said turnstile member being rotated by air flowing through saidperforations, and means for stopping the turnstile member from furtherrotation under the influence of said flowing air when a depending leg isrotated to a position in the path of articles moving along the conveyor.

1. An air conveyor comprising the combination of a conveyor surfacehaving perforations therein, means for supplying a flow of air throughsaid perforations to lift and move articles along said conveyor; and amomentum decelerator comprising a turnstile member having a plurality oflegs extending therefrom, said turnstile member being mounted forrotational movement above the conveyor surface so that the dependinglegs may contact and decelerate articles moving along the conveyor, saidturnstile member being rotated by air flowing through said perforations,and means for stopping the turnstile member from further rotation underthe influence of said flowing air when a depending leg is rotated to aposition in the path of articles moving along the conveyor.
 2. An airconveyor comprising the combination of a conveyor surface havingperforations therein, means for supplying a flow of air through saidperforations to lift and move articles along said conveyor; and amomentum decelerator comprising a turnstile member having a plurality oflegs extending therefrom, said turnstile member being mounted forrotational movement above the conveyor surface so that the dependinglegs may contact and decelerate articles moving along the conveyor, saiddepending legs being spaced from each other so that when a movingarticle on the conveyor contacts and rotates the turnstile member, afollowing leg on the rotating turnstile member contacts said movingarticle causing further deceleration of the article on the conveyor,said turnstile member being rotated by air flowing through saidperforations, and means for stopping the turnstile member from furtherrotation under the influence of said flowing air when a depending leg isrotated to a position in the path of articles moving along the conveyor.